The invention concerns a device for mutual locking of concentric cylindrical parts such as parts in a submersible pump unit.
A submersible pump unit normally includes an electrically driven motor and a hydraulic unit with a rotating impeller connected to the motor via a rotary driving shaft.
In order to prevent the medium within the hydraulic unit from penetrating the motor along the driving shaft, one or two seals are normally arranged between the motor and the hydraulic unit. A common type of seal is the so-called mechanical face seal, which includes one seal ring rotating with the shaft and one stationary seal ring attached to the surrounding housing. The two seal rings are pressed against each other by a spring, thus preventing medium from entering between the seal surfaces.
A pump unit of the above mentioned type will thus include an electric motor, a seal housing and a hydraulic unit with an impeller connected to the motor via a central rotary shaft.
In order to keep the different parts together into one unit there are several solutions. Big machines are normally kept together by help of flanges provided with a number of bolts along their circumferences. Smaller machines may be connected by help of long bolts around the periphery which bolts press the outer parts towards each other, thus locking the intermediate part therebetween.
Examples of such solutions are shown in SE- 415 696 and DE- 1 653 726.
A disadvantage with these known solutions is that they are relatively expensive because of costly materials and because of the fact that the mounting time could be extensive. The problem to be solved is thus to obtain a slim design without any outer details which add to its diameter.
A device for obtaining an axial locking between concentric details is disclosed in SE-399 745. An element 6 is here arranged within grooves in the concentric details thus establishing an axial mutual locking. A disadvantage however, is that said element 6 is rigid, which means that the concentric details are not allowed to come into contact with each other. The result will be that the mutual location of the details is not defined, but may vary depending on the dimension of the element 6. In addition there is no locking against mutual rotation.
A device for mutual axial and radial locking of an outer detail and two adjacent internal details, comprises a ring-shape locking spring element and a circumferentially formed channel disposed at an intersection between the outer detail and the internal details. The locking spring element is compressed in the channel.